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Know and Describe Group 1

Worksheet Overview

QUESTION 1 of 10

Group 1 of the periodic table contains some of the strangest elements there are. They are metals, but not as you know them…

The Group 1 elements are also called the alkali metals. They sit in the left-hand column of the periodic table. Reading from top to bottom, they are called lithium, sodium, potassium, rubidium, caesium and francium.

 

 

Like most metals, they are shiny and grey. The turn dull grey in a few seconds when they are exposed to air because they react very quickly with oxygen. That shows they are very reactive, but otherwise, this is normal behaviour for metals. The reactions follow this pattern;

 

lithium + oxygen → lithium oxide 

4 Li (s) + O2 (g) → 2 Li2O (s)

 

They conduct electricity, but nobody ever uses alkali metals to make electrical wires.

 

So what’s strange about them? First, some of them have a very low density; lithium, sodium and potassium all float in water, so they must be less dense than water. Secondly, they are very soft; you can cut them with a knife or scalpel as if they were a piece of cheese. As you go down group 1, the metals become even softer.

 

The strangest thing about the alkali metals is what happens when you put them in water. All the alkali metals react very vigorously with water, with reactions like these;

 

lithium + water → lithium hydroxide + hydrogen

2 Li (s) + 2 H2O (l) → 2 LiOH (aq) + H2 (g)

 

The hydroxide solutions made in this reaction turn the water alkaline. That’s why these metals are called alkali metals.

As you go down Group 1, this reaction becomes more energetic. Lithium fizzes, sodium fizzes a lot, potassium burns with a characteristic lilac (purple) flame.

A scientist once put a piece of caesium into a glass dish of water, and the reaction released so much energy that the dish shattered instantly.

The reason that the alkali metals behave this way is linked to the arrangement of electrons in shells. Let’s look at sodium as an example. Sodium is atomic number 11, so a sodium atom has 11 electrons. That’s 2 in the first shell, 8 in the second shell, and one in the third shell. We can write that as 2.8.1, or draw a picture like this;

 

 

In fact, all the alkali metals have 1 electron in their outermost shell. Lithium is atomic number 3, so its electron configuration is 2.1. Potassium is atomic number 19, which is 2.8.8.1. The same goes for the heavier alkali metals.

 

That single electron in the outermost shell is very unstable. All the alkali metals need to lose their outermost electron. Since there is only one electron to lose, it can happen fairly easily, and this process releases lots of energy. For the heavier alkali metals, there is quite a long distance between the atomic nucleus and the outermost shell, so the outer electron is only loosely attached to the nucleus. That means that all the alkali metals are all reactive, and the heavier alkali metals are the most reactive of all.

What is the other name for Group 1 elements?

Alkali metals

Halogens

Transition metals

Which is the least reactive alkali metal?

Potassium

Caesium

Lithium

Sodium

Tick two products of the reaction of lithium with water.

Carbon dioxide

Hydrogen

Lithium

Lithium hydroxide

How many electrons are in the outer shell of a Group 1 element? 

1

2

3

4

Select the two reactants of the reaction that produces lithium chloride.

Lithium

Potassium

Iodine

Chlorine

What is the correct symbol for sodium oxide? 

NaO

KO

Na2O

K2O

What is the correct symbol for potassium chloride

KO

KCl

K2Cl

Which of these alkali metals is the softest? 

Li

K

Na

Complete this equation:

 

Potassium + water ___________ + hydrogen

Potassium oxide

Potassium hydroxide

Potassium chloride

Complete this equation:

 

2 K +2 H2_________ + _________

Potassium oxide

Potassium hydroxide

Potassium chloride

  • Question 1

What is the other name for Group 1 elements?

CORRECT ANSWER
Alkali metals
EDDIE SAYS
Group 1 elements are called Alkali Metals. They are called this because they make an alkali when they react with water.
  • Question 2

Which is the least reactive alkali metal?

CORRECT ANSWER
Lithium
EDDIE SAYS
Lithium is the least reactive alkali metal. Caesium is the most reactive metal. As we go down Group 1, alkali metals get more reactive.
  • Question 3

Tick two products of the reaction of lithium with water.

CORRECT ANSWER
Hydrogen
Lithium hydroxide
EDDIE SAYS
Two products of the reaction of lithium with water are hydrogen and lithium hydroxide. Remember the general equation of metal + water -> metal hydroxide + hydrogen. Just replace the word metal with the group 1 metal you are using!
  • Question 4

How many electrons are in the outer shell of a Group 1 element? 

CORRECT ANSWER
1
EDDIE SAYS
Group 1 elements are called group 1 because they all have 1 electron in their outer shell. 1 electron, Group 1.
  • Question 5

Select the two reactants of the reaction that produces lithium chloride.

CORRECT ANSWER
Lithium
Chlorine
EDDIE SAYS
In order to get lithium chloride, one must react lithium and chlorine. You can tell by the name of the product, which is a compound of lithium and chlorine. We say chloride, because the chlorine has been turned into an ion.
  • Question 6

What is the correct symbol for sodium oxide? 

CORRECT ANSWER
Na2O
EDDIE SAYS
Group 1 elements always make a product that is metal with a little 2 and then oxygen. You will learn why when you look at Ionic bonding.
  • Question 7

What is the correct symbol for potassium chloride

CORRECT ANSWER
KCl
EDDIE SAYS
When group 1 reacts with chlorine, you will always get the metal symbol followed by Cl without any numbers. You will learn why this happens when you look at ionic bonding.
  • Question 8

Which of these alkali metals is the softest? 

CORRECT ANSWER
K
EDDIE SAYS
As you go down the group, the metals become softer. Be careful though, there's a red herring here - they are not in the correct order!
  • Question 9

Complete this equation:

 

Potassium + water ___________ + hydrogen

CORRECT ANSWER
Potassium hydroxide
EDDIE SAYS
Remember the general equation: metal + water -> metal hydroxide + hydrogen.
  • Question 10

Complete this equation:

 

2 K +2 H2_________ + _________

CORRECT ANSWER
EDDIE SAYS
That's right, you need to know the symbols as well! But you're good enough at learning to cope with that. Hydroxide symbols are Metal and the OH (hydrogen and oxygen or hydroxide). We need the factors of 2 to balance the equation- making sure that there are equal numbers of atoms on each side.
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